186 H. LEIGHTON KESTEVEN. 
retention of the phyloconch, which it is unnecessary to detail 
here. In the following instances it is not known whether or 
not the phyloconch is retained. 
Murex denudatus (Perry) presents us with a protoconch 
consisting of veloconch and nepioconch, the latter being 
represented by a varix (8). 
The protoconch of Triphorais aveloconch; a portion of it 
in some species exactly resembles the adult shell, or true 
conch (2 and 5). 
The protoconch of Lotorium is composed as follows :— 
In the veliger stage veloconch; in early neanic stages, neano- 
conch and veloconch, the former inside the latter; in stages 
later than ananeanic, of neanoconch only, the veloconch having 
by that time been shed (4). 
In Megalatractus aruanus (Linn) the protoconch isa 
neanoconch, but if it be taken from the egg capsule the 
calcareous cast of the veloconch will often be found attached 
to the apical whorl. ‘The shedding of the calcareous cast of 
the veloconch of this species is particularly interesting ; it is 
parallelled by nothing so exactly as the decay of, and deposit 
of fresh dentine by, the human tooth. As the outer layer of 
lime is shed, a fresh layer is deposited inside it. I drew 
attention to this fact when describing the protoconch, in my 
recent Report on the anatomy of Megalatractus (6). 
In Number III of ‘Notes on Prosobronchiata’ (5), I 
proposed the term “ pseudoprotoconch” for the neano- 
conch of Lotorium, but my study of that of Megala- 
tractus has shown me that a protoconch may be a neanic 
structure and yet not a cast of a corneous veloconch. I 
therefore wish to withdraw the term, in favour of the more 
explicit one, “ neanoconch.” 
p. A Drepuctive Mrruop or StupyInG THE Karty Lire History 
OF A GASTROPOD. 
Except by a study of the early development of the mollusc, 
itis unlikely that it can be ascertained whether or not the 
